Circuit-breakers having magnetic blow-out means



A. LATOUR June 16, 1964 CIRCUIT'BREAKERS HAVING MAGNETIC BLOW-OUT MEANS Filed Sept. 26, 1958 2 Sheets-Sheet 2 INVENTOR ANDRE LATOUR I ATTORNEY United States Patent 3,137,779 CIRCUIT-BREAKERS HAVING MAGNETIC BLOW-OUT MEANS Andr Latour, 18 Ave. Felix Viallet, Grenoble, France Filed Sept. 26, 1958, Ser. No. 763,603 Claims priority, application France Nov. 5, 1957 1 Claim. (Cl. 200144) This invention relates to circuit-breakers and more particularly to circuit-breakers having magnetic blow-out means and comprising an arc formation chamber wherein the arc is drawn and elongated during the opening movement of the contacts and an arc extinction chamber into which the arc is forced by the effect of the magnetic field, this are extinction chamber being provided with means to cause supplementary elongation and/or the cooling of the arc.

The primary object of the present invention is to insure the operation of the circuit-breakers in the presence of a compressed gas or of gases with large molecules (known as electro-negative gases) and the counter-balance the unfavorable effects which are caused by the presence of an atmosphere under pressure, and which slows down the speed of displacement of the arc and, consequently, the speed of deionization of the atmosphere where the arc moves, whereby the time of interruption is increased and the interrupting capacity of the circuitbreaker is reduced.

Another and more distinct object of the invention is to provide a circuit-breaker wherein the arc formation chamber and the arc extinction chamber are joined together and have different cross sectional areas.

This object is attained according to the invention by the combination of the following two structures:

(1) by providing an arc formation chamber and an arc extinction chamber which are closely joined by passages whose section is different from the section of the arc formation chamber taken in a plane perpendicular to the plane wherein the arc moves, and parallel to the direction in which the movable contact moves;

(2) by closing on all sides the arc formation chamber with the exception of the side where the arc formation chamber opens into the arc extinction chamber.

As a consequence of the second measure, the energy developed by the are results in an increase of the pressure within the arc formation chamber and in the production of an air current which, as the arc formation chamber is closed on all sides, can only escape into the arc extinction chamber. This current of air tends to move the arc with a higher speed into the arc extinction chamber and so compensates the slow-down of the arc movement, which may be expected in the arc formation chamber, particularly in the case of the interruption of heavy currents.

Applicants have found that it is advantageous to inject into the arc formation chamber a blast of air of relatively high pressure. This pressure should be, at least, of the order of the pressure applied in the well known switches with self-blast. The gas blast for the power circuit-breaker may be produced by the breaker itself or provided by an appropriate compressed air source.

It is known in the art of circuit-breakers with magnetic blow-out operating under normal atmospheric conditions, to increase the effect of the magnetic blow-out by a supplementary pneumatic blowing device, for example, a bellows which produces a current of air of very low pressure, intended to facilitate the displacement of the arc towards the arc extinction chamber, particularly in the case where the arc currents are small. Such a device, of course, cannot be applied in the present case where relatively high pressure is to be developed in the arc formation chamber.

3,137,779 Patented June 16, 1964 The invention will be described with reference to the accompanying drawings, in which:

FIGURE 1 is an elevation in section of a circuit-breaker according to the invention, the contacts being shown in a position at the instant where they are going to separate,

FIGURE 2 is a view of a section of the arc extinction chamber along the line IIII of FIGURE 1, only some of the cooling plates of the chamber are there shown,

FIGURE 3 is a cross section of a circuit-breaker taken along the line IIIIII of FIGURE 1,

FIGURE 4 is an elevational section of a circuit-breaker with supplementary devices for production of a gas blast, the contacts being shown in the position which precedes their separation, and

FIGURE 5 shows another embodiment of the invention wherein the circuit-breaker is provided with arcing contacts.

In the figures, the arc extinction chamber is designated by reference character 1. This arc extinction chamber is well known from the circuit-breakers marketed under the trade name Solenarc and comprises a number of cooling plates 2 parallel to each other and perpendicular to the plane wherein the arc is drawn on separation of the contacts. The cooling plates are provided, at their lower borders, with V or U-shaped conducting elements 3 and between the plates and above these conducting elements 3 sulfifficient space is provided to allow the divisional arcs to develop into large, nearly closed loops.

The arc formation chamber 4 is placed adjacent and below the arc extinction chamber 1, and comprises the usual arcing horns 5 and 6 fixed between lateral closing walls 7 and 8 (FIGURE 3). The chamber 4 is completely closed at its bottom side by a U-shaped wall 9. The movable contact is designated by the numeral 10. It is actuated by a mechanism placed outside chamber 4 and not shown, as it does not belong to the invention.

With the movable contact 10 cooperates a semi-movable contact piece 12 placed outside the arc formation chamber 4 and controlled by a spring 13. In the closed position of the circuit-breaker the two contacts 10 and 12 take the same position as the contact pieces 31 and 32 shown in FIGURE 5, the spring 13 being compressed. At the instant where the two contacts part the contact piece 12, urged by the spring 13, is pressed against the walls of the chamber 4 and chokes the opening through which has passed the contact piece 10. The magnetic blow-out device has not been shown. This device becomes unnecessary under certain operating conditions of the disclosed breaker, which is another advantage of the present invention.

The circuit-breaker operates as follows:

When the contacts part, an arc is drawn between the pieces 10 and 12 which almost immediately jumps onto the arcing horns 5 and 6 and under the action of the magnetic field moves upwards and is elongated. When the arc has reached the conducting elements 3 it is split up into divisional arcs and each divisionary arc, because of the arrangement of the two branches of two consecutive elements, is turned by moves upwards and develops into a large, nearly closed loop, so that the arc is considerably elongated and, at the same time, strongly cooled by the plates 2 and rapidly extinguishes.

The are formation chamber is fully closed with the exception of the top, which opens into the arc extinction chamber. The energy developed by the arc causes an over-pressure because the spacings between the plates 2 are very small (about 2 to 3 mm.) and because the upper parts of the divisional arc extinction chamber are provided with flame-arresters which still further narrow the section of the passage between two adjacent plates. Such a fiame-arrester is shown in FIGURE 1 as 14. Thus, an

upward directed stream of hot air or gas is produced which favors the upward movement of the are by an overpressure which may be more or less high according to how the circuit-breaker has been designed.

In FIGURE 4, a circuit-breaker is shown provided with a supplementary device for pneumatic self-blast. The device comprises a piston 21. This piston is integral with the movable contact 10 which functions at the same time as a piston rod. The contact 10 is hollow and opens at one end into the cylinder space 22 and is provided at the other end with an orifice 23 opening into the arc formation chamber 4.

The circuit-breaker operates as follows:

When the contact pieces 10 and 12 part, the air in the cylinder 22 is compressed and 'a blast of compressed air flowing through the hollow contact 22 and the orifice 23 is directed into the arc formation chamber 4. This blast reinforces the effect of the upward directed air stream produced by the heat generated by the are so that the arc is driven with an increased force into the arc extinction chamber.

FIGURE shows a circuit-breaker according to the invention similar to the circuit-breaker illustrated in FIG- URE 4 but provided with arcing contacts. The main contacts 33 and 34, as well as the semi-fixed arcing contact 32, are located outside the arc formation chamber. The interruption of the current occurs in a known manner: the main contacts 33 and 34 parting first Without production of an arc and the current interruption being achieved by the arcing contacts 31 and 32, the are being drawn between these contacts and within the arc formation chamber 4. The movement of the movable main contact 34 and of the movable arcing contact 31 may be coupled by any convenient mechanical means.

It is, of course, possible to make the walls of the arc formation chamber partially or Wholly of a material generating gases under the thermal effects of the arc to thereby increase the pressure in the chamber.

What is claimed is:

A magnetic circuit-breaker including an arc chute comprising, in combination, an arc formation chamber including at least one movable contact and stationary arcing horns leading generally in an upward direction, the said chamber being totally enclosed except for the top thereof along a slot having the length of the break distance, an arc extinction chamber joined to said arc formation chamber at the top and in direct communication therewith through said slot and including an arc chute, the cross sectional horizontal dimension of the arc extinction chamber being larger than the cross sectional dimension of the arc formation chamber taken along a plane normal to the direction of motion of the movable contact, said movable contact being slidably mounted for movement through a chamber wall, a second contact being disposed outside and adjacent to said are formation chamber, and resilient means pressing said second contact against the Wall of said are formation chamber to seal the chamber opening through which the movable contact retracts; both recited contacts being disposed to contact one with the other in the circuit-closed position of said movable contact.

References Cited in the file of this patent UNITED STATES PATENTS 1,967,989 Clerc July 24, 1934 2,253,197 Prince Aug. 19, 1941 2,272,224 Rankin Feb. 10, 1942 2,345,724 Baker et a1. l Apr. 4, 1944 2,382,850 Bennett Aug. 14, 1945 2,445,529 Leeds July 20, 1948 2,660,647 Rawlins Nov. 24, 1953 2,850,600 Prince Sept. 2, 1958 FOREIGN PATENTS 451,431 Great Britain Aug. 6, 1936 499,664 Great Britain Jan. 26, 1939 534,501 Great Britain Mar. 7, 1941 575,854 Great Britain Mar. 7, 1946 44,831 France Jan. 19, 1935 801,592 France May 23, 1936 

